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NUTRITION
THE SCIENCE OF NUTRITION
Nutrition as a science is a new and emerging field of study about how
the body functions and what nourishment it needs for maximum
performance. The study of nutrition in the past was concerned with
vitamin deficiency diseases, such as scurvy, rickets, pellagra, beri beri
and malnutrition. Study of these diseases and their possible causes
eventually led to more knowledge of nutrients.
The diseases that began the research are now almost unknown in this
country. With food more easily obtained that in earlier years, the main
focus of nutrient research now is more frequently of conditions caused
by an over indulgence in rich, processed foods. Examples of some
current health concerns are obesity, heart disease and cancer.
Scientists announce new treatments for life-threatening illnesses and
the results of research studies regularly. Knowledge about how your
body works and the nutrients that keeps it functioning will help you
understand some of these new developments and how they might affect
you. Good food choices will help you be healthy and energetic and get
the most out of life.
THE NUTRIENTS
CARBOHYDRATES
Carbohydrates include sugars, starches and fiber and are the body’s
prime source of energy. They are found mainly in cereal grains and
vegetables and fruit. Carbohydrates are the cheapest and most easily
digested form of fuel. They are often classified according to their
composition – Simple and complex.
SIMPLE CARBOHYDRATES
Simple carbohydrates are all sugars. Some of them are sucrose (cane or
beet sugar), lactose (milk sugar) and fructose (fruit sugar). The
simplest form is glucose, the form in which carbohydrates are
eventually absorbed and transported through the body.
Simple carbohydrates are sometimes referred to disaccharides, meaning
tow sugar molecules, and monosaccharides, meaning one sugar
molecule. Disaccharides are a form of sugar such as sucrose, maltose
and lactose. Monosaccharides are simplest sugars such as glucose,
fructose, and galactose.
COMPLEX CARBOHYDRATES
Complex carbohydrates are made up of large molecules of simple
carbohydrates joined together. Examples are starches, cellulose,
glycogen, and dextrins. These are digested into simpler forms before
they are absorbed by the body for use. They are preferred for good
health because they take longer to digest and help maintain a steady
blood sugar level. This keeps your energy up for daily activities and you
do not feel tired. Complex molecules having several sugar molecules
such as those found in starches and fiber are sometimes called
polysaccharides.
Humans cannot digest some complex carbohydrates such as cellulose.
They do however provide bulk to aid elimination.
PROTEIN
Protein is important for growth and repair of the body’s cells and
tissues. It is used to make hormones, enzymes and antibodies. A
secondary function is to provide energy. When there are not enough
carbohydrates in the diet and fat stores are used up, protein from foods
is used for energy instead of for building and repair.
Proteins are made up of large numbers of units, called amino acids. That
are linked together. During digestion, proteins are broken down into
amino acids, which are absorbed through the intestinal wall. When the
body needs to build or repair human tissue, it draws from the pool of
absorbed amino acids.
Different proteins contain different forms of amino acids. They can be
divided into two types.
ESSENTIAL AMINO ACIDS